1. Field of the Invention
The present invention relates generally to devices for spreading or dispensing particulate matter upon a traversed terrain, and in particular to a device for top dressing turf.
2. Description of the Prior Art
Top dresser devices utilizing a wide variety of technologies are well known in the art. One particular class of top dressers includes a frame-mounted hopper for receiving particulate matter, a flexible belt for transporting the particulate matter along the hopper, and a brush assembly for dispensing the particulate matter as it is conveyed along the belt. Yet another class of top dressers includes a tow-behind variety, wherein a top dresser device is disposed upon a towable frame and drawn across the terrain by a traction vehicle. Power for the belt and brush assemblies may be external or internal to the top dresser. An external power source may, for example, be an accessed hydraulic system of the traction vehicle. Alternatively, internal power sources may include a separate internal combustion engine or a ground driven mechanism. Generally, the term xe2x80x9cground drivenxe2x80x9d refers to the interaction of an apparatus as it moves relative to the ground; in this instance, the support wheels of a top dresser as they roll along the ground. Ground driven mechanisms may include systems for mechanically or hydraulically coupling the support wheels of a top dresser to provide power other components of the top dresser during operation. In a hydraulic powered ground driven top dresser, for example, support wheels may be coupled to hydraulic pumps to provide pressurized fluid to drive the top dresser.
Prior art top dressers present several substantial limitations. One limitation of hydraulic power based ground driven top dressers is the requirement of an adequate supply of pressurized fluid to the inlet ports of the wheel driven pumps. It has been recognized that inlet fluid pressurization is needed to charge the wheel driven hydraulic pumps to prevent cavitations, dry runs, etc., and for this reason supply reservoirs have been pressurized. Reservoir pressurization presents relatively few problems during top dresser operation. However, reservoir pressurization may promote leakage within the system, particularly at the wheel driven hydraulic pumps whenever the top dresser is inactive. This is particularly problematic because hydraulic fluid may damage turf surfaces. Furthermore, the use of fluidic systems which have pressurized containers may require periodic inspection, certification and/or regulatory compliance before they can be introduced into certain markets.
Another limitation of prior art top dressers has been impaired machine operation over uneven or irregular terrain. In such terrain, a tire may temporarily lift away from or xe2x80x9cskipxe2x80x9d over the ground and tear or scuff the turf when the tire re-contacts the turf surface. Another limitation related to skipping is the uneven distribution of weight that occurs between the adjacent tires when the top dresser traverses over undulating terrain. As the top dresser traverses such terrain and one of the tires is unable to maintain contact with the ground, all of the weight that is normally supported by the adjacent tires must now be supported by the tire(s) which remains in contact with the ground. This reduces the ground contact area and increases the ground contact pressure. Turf rutting or other damage may result as the weight of the top dresser is transferred to the other tires(s) in contact with the ground.
Yet another limitation of some prior art top dressers is the inability to evenly distribute material at a substantially consistent predetermined application or coverage rate (e.g., lbs. of top dressing material per square yard of turf) irrespective of the speed at which the top dresser is being moved relative to the terrain. In this regard, in order for the application rate (lbs. per square yard) to be consistent, the distribution rate (lbs. per second) of material exiting the top dresser needs to be proportional to the ground speed (feet per second) of the top dresser. Operation of some prior art ground driven top dressers at varying ground speeds may result in uneven distribution of material upon the turf surface. For example, an application rate greater than desired when the top dresser slows below a nominal operating ground speed, or an application rate less than desired when the top dresser exceeds a nominal operating ground speed. Particular solutions to the problem have included unduly complex regulating mechanisms which are difficult to maintain and prone to breakdown. Known regulating mechanisms may include clutches, chains, and shafts, each of which are especially prone to damage in hostile environments.
Another related limitation of some prior art top dressers is the inability to accommodate nonconformities such as large rocks or other debris mixed in with the top dressing material. This is not an unusual or rare occurrence because top dressing material is typically stored outdoors and is susceptible to many forms and sources of contamination. Large rocks or debris contained within a mixture of top dressing material may become lodged at the metering gate mechanism resulting in uneven material distribution and/or damage to the conveyer belt and the gate mechanism. Thus, an operator of a top dresser must not only keep a watchful eye on the distribution rate, but is compelled to periodically stop the top dresser and inspect the gate mechanism for nonconformities. This may result in significant down time even if the inspection does not reveal any nonconformities. One time consuming approach in dealing with nonconformities may be to pre-condition or pre-screen the top dressing material prior to, or during loading of the hopper of a top dresser. Another approach may be to store the top dressing material in a controlled environment.
Another limitation of some prior art top dressers concerns the effort required to install a conveyer belt on the top dresser, as during initial manufacture, or replacement of a worn or damaged belt. Initial installation and replacement or repair of worn or damaged belts has generally been a tedious and time-consuming task, at best. Often, a top dresser must be substantially dismantled in order to access a conveyor belt and its attendant roller assemblies. This process may also require specially designed fixtures, equipment and trained personnel to make the necessary repairs and/or replacement, and may result in significant down time.
Another limitation of some prior art top dresser concerns the longevity or working life of the conveyer belt. The typical prior art conveyor belt is formed by taking opposing ends of a length of suitable material and joining them together by well known linking or seaming techniques, including mechanical link structures. Conveyer belts often degrade at or near the links, as the structures are generally more rigid than the belt material. Additionally, conveyor belts may fail or be damaged due to imperfections, the use of incompatible linking materials, extremes in temperature, stretching, etc. A need therefore exists for a conveyer belt having improved durability provided by an elimination of a mechanical linking structure.
In summary, there is a need for a top dresser with support wheels which do not skip or scuff as they travel along uneven terrain. Still a further need exists for a top dresser which is able to distribute particulate matter at a predetermined application rate irrespective of the speed of the top dresser. A need also exists for a top dresser with a dispensing apparatus which is able to accommodate large nonconformities effectively and efficiently. Additionally a need exists for a top dresser which has a conveyor belt which less susceptible to premature separation and which is easy to access and service. And there is still further a need for a top dresser with a hydraulic circuit which is less prone to fluid leakage during periods of inactivity.
A top dresser for distributing particulate matter on a variety of terrain. In one embodiment, the top dresser includes a towable frame which is operatively connected to a pair of wheel assemblies. Each wheel assembly is rotatingly attached to the frame of the top dresser in such a fashion as to enable the wheels of the wheel assembly to follow the contours and undulations in the terrain over which it traverses. Each wheel assembly is operatively connected to a power converter such as a hydraulic pump or an electrical generator which is, in turn, operatively connected to a hydraulic or electrical circuit, as the case may be, which is used to control and power various elements of the top dresser.
A top dresser according to the present invention includes a hopper with a metering gate assembly and a conveyor to distribute particulate matter at predetermined rates to the terrain. The gate assembly is adjustable and includes a gate which is temporarily displaced in response to large nonconformities such as rocks. The conveyor belt is a pre-manufactured xe2x80x9cseamlessxe2x80x9d or continuous loop of material having a patterned or otherwise roughened surface for conveying the particulate matter. The conveyer belt is termed xe2x80x9cseamlessxe2x80x9d in that no external link structure is necessary to join the ends of the belt material to form the belt loop. The conveyer belt is movably supported between a pair of roller assemblies, including a drive roller assembly having a metal oxide surface for enhancing the friction coefficient between the roller and the conveyer belt. The conveyor belt and the attendant roller assemblies may be accessed by shifting a portion of the top dresser, and the conveyor belt and attendant roller assemblies may be in turn shifted to permit replacement, repair and inspection. A hydraulic circuit is provided with a charge pump assembly which eliminates the need to maintain a pressurized reservoir, thus reducing leakage during periods of inactivity.
Accordingly, it is an object of the present invention to provide an improved granular material spreader that is efficient in operation across a variety of terrain. In particular, a towable top dressing device is provided having a pair of wheel sets or assemblies which may independently follow the contours of uneven terrain. In one preferred embodiment, each pair of wheel sets or assemblies may undergo a xe2x80x9crollingxe2x80x9d motion relative to the frame and other wheel set to maintain contact with the ground. It is another aspect of the present invention to minimize the uneven distribution of weight between the wheels of a towed top dresser.
It is another object of the present invention to provide a towable, vehicle-mounted, or self-propelled top dresser which evenly distributes material at a substantially constant predetermined coverage rate (e.g., lbs. of top dressing material per square yard of turf) irrespective of the speed at which the top dresser is moved relative to the terrain. In this regard, in order for the application rate (lbs. per square yard) to be consistent, the distribution rate (lbs. per second) of material exiting the top dresser needs to be proportional to the ground speed (feet per second) of the top dresser.
Another object of the present invention is to provide an improved gate assembly for permitting the top dresser to distribute top dressing material which may have nonconformities such as rocks or other debris incorporated therein. The improved gate assembly includes a biased gate relief assembly or release device which is temporarily displaceable to permit nonconformities or outsized objects such as rocks and debris to pass thereby with minimal risk of damage to the conveyor belt and gate assembly of the top dresser. In this regard, the top dresser of the present invention is able to use top dressing mixtures which would otherwise require preconditioning prior to application.
It is another object of the present invention to provide a ground driven hydraulic power based top dresser having an improved hydraulic circuit for selectively powering a conveyor belt and a brush assembly. An improved hydraulic circuit eliminating the necessity of a pressurized reservoir system is provided in an embodiment of the present invention. Additionally, a feature of the hydraulic circuit is that it is able to assist in braking the utility vehicle and top dresser under some conditions.
It is yet another object of the present invention to decrease the amount of down-time by the use of a longer lasting conveyor belt with improved access thereto for maintenance and replacement.
These and further objects and advantages of the present invention will become clearer in light of the following detailed description of preferred embodiments in connection with the drawings.